First, you should be proud of yourself for wanting to finish your A levels.
Since you are in your 30s, you might want to ask yourself what do you hope to achieve with the A levels?
Is it self satisfaction of having completed them OR are the. A levels to help you get to the next step, may be a degree ?
If I were you I would have a long hard think about this. You might find that your work experience can get you onto an associate degree or a university certificate course.
There are so many options available out there.
Also, check out coursera.com. and edx.org where you can sign up and complete university course components. You can get the official certificate if you complete all the assignment and pay for the certificate. Or you can do the courses for free.
A lot of these courses also count towards CPD points (continuous professional development).
These are short courses and will give you a boost and also may open your eyes into another course direction.
There are also a lot of online A level courses for the UK. However, I don't know much about them.
Really, think where you want to be ....then think what you need to get there. A levels might not be needed.
Good luck .